[PATCH] commit, status: #comment diff output in verbose mode

[Ian Ward Comfort <icomfort@stanford.edu>]

On 3 Mar 2011, at 3:12 AM, Sverre Rabbelier wrote:
> On Thu, Mar 3, 2011 at 04:50, Junio C Hamano <gitster@pobox.com> wrote:
>> Good question.  There was no reason other than "that is just a historical
>> accident".
>>
>> The intention has always been "allow people to review the change for the
>> last time while writing a log message"; there was never a feature request
>> to allow the diff to be included---it would always have been an unwelcome
>> accident it that ever happened.
>
> In that case, can we change it to be that way now if it makes this case
> easier?

How about something like this?

--8<--

By historical accident, diffs included in commit templates and status
output when the "-v" option is given are not prefixed with the # comment
character, as other advice and status information is. Stripping these
lines is thus a best-effort operation, as it is not always possible to
tell which lines were generated by "-v" and which were inserted by the
user.

Improve this situation by adding the # prefix to diff output along with
all other status output in these cases. The change is simply made thanks
to a3c158d (Add a prefix output callback to diff output, 2010-05-26). The
prefixed diff can be stripped (or not, as configured) by the standard
cleanup code, so our special verbose-mode heuristic can be removed.

Documentation and a few tests which rely on the old "-v" format are
updated to match. One known breakage is fixed in t7507.

Signed-off-by: Ian Ward Comfort <icomfort@stanford.edu>
---
 Documentation/git-commit.txt |    3 +--
 builtin/commit.c             |    7 -------
 t/t4030-diff-textconv.sh     |    2 +-
 t/t7502-commit.sh            |    4 ++--
 t/t7507-commit-verbose.sh    |    4 ++--
 wt-status.c                  |   12 ++++++++++++
 6 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index 8f89f6f..792f993 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -233,8 +233,7 @@ configuration variable documented in linkgit:git-config[1].
 --verbose::
 	Show unified diff between the HEAD commit and what
 	would be committed at the bottom of the commit message
-	template.  Note that this diff output doesn't have its
-	lines prefixed with '#'.
+	template.
 
 -q::
 --quiet::
diff --git a/builtin/commit.c b/builtin/commit.c
index 355b2cb..efecac3 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1381,13 +1381,6 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		die("could not read commit message: %s", strerror(saved_errno));
 	}
 
-	/* Truncate the message just before the diff, if any. */
-	if (verbose) {
-		p = strstr(sb.buf, "\ndiff --git ");
-		if (p != NULL)
-			strbuf_setlen(&sb, p - sb.buf + 1);
-	}
-
 	if (cleanup_mode != CLEANUP_NONE)
 		stripspace(&sb, cleanup_mode == CLEANUP_ALL);
 	if (message_is_empty(&sb) && !allow_empty_message) {
diff --git a/t/t4030-diff-textconv.sh b/t/t4030-diff-textconv.sh
index 88c5619..b00999e 100755
--- a/t/t4030-diff-textconv.sh
+++ b/t/t4030-diff-textconv.sh
@@ -79,7 +79,7 @@ test_expect_success 'format-patch produces binary' '
 test_expect_success 'status -v produces text' '
 	git reset --soft HEAD^ &&
 	git status -v >diff &&
-	find_diff <diff >actual &&
+	sed -e "s/^# //" <diff | find_diff >actual &&
 	test_cmp expect.text actual &&
 	git reset --soft HEAD@{1}
 '
diff --git a/t/t7502-commit.sh b/t/t7502-commit.sh
index 50da034..a916001 100755
--- a/t/t7502-commit.sh
+++ b/t/t7502-commit.sh
@@ -151,8 +151,8 @@ test_expect_success 'verbose' '
 
 	echo minus >negative &&
 	git add negative &&
-	git status -v | sed -ne "/^diff --git /p" >actual &&
-	echo "diff --git a/negative b/negative" >expect &&
+	git status -v | sed -ne "/^# diff --git /p" >actual &&
+	echo "# diff --git a/negative b/negative" >expect &&
 	test_cmp expect actual
 
 '
diff --git a/t/t7507-commit-verbose.sh b/t/t7507-commit-verbose.sh
index da5bd3b..5b21bbb 100755
--- a/t/t7507-commit-verbose.sh
+++ b/t/t7507-commit-verbose.sh
@@ -5,7 +5,7 @@ test_description='verbose commit template'
 
 cat >check-for-diff <<EOF
 #!$SHELL_PATH
-exec grep '^diff --git' "\$1"
+exec grep '^# diff --git' "\$1"
 EOF
 chmod +x check-for-diff
 test_set_editor "$PWD/check-for-diff"
@@ -65,7 +65,7 @@ test_expect_success 'diff in message is retained without -v' '
 	check_message diff
 '
 
-test_expect_failure 'diff in message is retained with -v' '
+test_expect_success 'diff in message is retained with -v' '
 	git commit --amend -F diff -v &&
 	check_message diff
 '
diff --git a/wt-status.c b/wt-status.c
index a82b11d..fc0063e 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -32,6 +32,12 @@ static const char *color(int slot, struct wt_status *s)
 	return c;
 }
 
+static struct strbuf *diff_output_prefix_callback(struct diff_options *opt, void *data)
+{
+	assert(data);
+	return (struct strbuf *)data;
+}
+
 void wt_status_prepare(struct wt_status *s)
 {
 	unsigned char sha1[20];
@@ -588,6 +594,7 @@ static void wt_status_print_verbose(struct wt_status *s)
 {
 	struct rev_info rev;
 	struct setup_revision_opt opt;
+	struct strbuf diff_output_prefix = STRBUF_INIT;
 
 	init_revisions(&rev, NULL);
 	DIFF_OPT_SET(&rev.diffopt, ALLOW_TEXTCONV);
@@ -596,10 +603,14 @@ static void wt_status_print_verbose(struct wt_status *s)
 	opt.def = s->is_initial ? EMPTY_TREE_SHA1_HEX : s->reference;
 	setup_revisions(0, NULL, &rev, &opt);
 
+	strbuf_addstr(&diff_output_prefix, "# ");
+
 	rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
 	rev.diffopt.detect_rename = 1;
 	rev.diffopt.file = s->fp;
 	rev.diffopt.close_file = 0;
+	rev.diffopt.output_prefix = diff_output_prefix_callback;
+	rev.diffopt.output_prefix_data = &diff_output_prefix;
 	/*
 	 * If we're not going to stdout, then we definitely don't
 	 * want color, since we are going to the commit message
@@ -609,6 +620,7 @@ static void wt_status_print_verbose(struct wt_status *s)
 	if (s->fp != stdout)
 		DIFF_OPT_CLR(&rev.diffopt, COLOR_DIFF);
 	run_diff_index(&rev, 1);
+	strbuf_release(&diff_output_prefix);
 }
 
 static void wt_status_print_tracking(struct wt_status *s)
-- 
1.7.4.1.177.g1c06f